1. Field of the Invention
This invention relates to a process for converting butane to acetic acid.
2. Description of the Prior Art
Processes for the oxidation of butane to acetic acid are known, but, invariably, such processes require excessively high temperatures and result in an oxygenated product mixture containing not only varying quantities of acetic acid but also oxygenated compounds including additional acids, such as formic acid, propionic acid and butyric acid; ketones, such as methyl ethyl ketone; alcohols, such as methanol, ethanol and isopropanol; esters resulting from the reaction of such acids with such alcohols; aldehydes, such as formaldehyde; etc.
A process that would appear to be feasible at low temperatures, that is, a temperature as low as about 150.degree. F. (65.degree. C.) is described in U.S. Pat. No. 3,293,292 of Olivier et al, which issued Dec. 20, 1966, but the reaction requires that butane be oxidized in the presence of a relatively complex catalyst system that includes bromine, cobalt and manganese and the product obtained contains undesirable amounts of ester. Each of the specific examples in the Olivier et al patent, however, is carried out at a temperature of 350.degree. F. (177.degree. C.). Since the latter temperature is relatively high we have attempted to carry out the reaction at a much lower temperature, that is, at 212.degree. F. (100.degree. C.) but without success. Thus, we have subjected 156 grams of butane to a temperature of 212.degree. F. (100.degree. C.) and an oxygen pressure of 300 pounds per square inch gauge in the presence of 1.65 grams of cobalt acetate tetrahydrate, 1.65 grams of manganese acetate tetrahydrate, 1.65 grams of ammonium bromide and 278 grams of acetic acid for 275 minutes but found no evidence that a reaction had occurred
British Pat. No. 709,674 attempts to oxidize a lower hydrocarbon in oxygen under such conditions that water formed as a product of oxidation is removed from the reaction mixture substantially as it is formed, but relatively low yields of desired acid are obtained and recycling of large amounts of unreacted hydrocarbon is required.